The perception of speech and language requires normal functioning of the primary auditory cortex. Many disorders lead to speech and language disorders and it is likely that some affect the wiring and function of the auditory cortex. Thus to understand how these deficits develop and to devise novel treatment approaches one has to understand the function of the auditory cortex. The auditory cortex contains millions of neurons and one challenge has been to identify what sound stimulus every neuron is responsive to and how neurons of different response properties are organized in the auditory cortex. Our studies will uncover how auditory cortex is organized and how complex sound stimuli such as speech stimuli are represented in auditory cortex. By using advanced imaging technology we will be able to account fully for the activity of all neurons in a cortical region and thus will be able to better understand the functional circuitry that processes auditory inputs. By studying these circuits over the developmental period and during plasticity tasks we will be able to learn how the circuitry of auditory cortex is changing and maturing. This is crucially important information, since early deficits in peripheral auditory processing can lead to altered wiring of cortical circuits. To be able to correct these potentially miswired circuits we have to understand which circuits are present during development and how they process the sensory information. Our proposed experiments lay the fundamental groundwork for a better understanding of auditory cortex by studying for the first time the large-scale organization and plasticity of auditory cortex with single cell resolution. PUBLIC HEALTH RELEVANCE: The perception of speech and language are of crucial important for human communication. Many disorders lead to speech and language disorders and it is likely that some affect the wiring and function of the auditory cortex. Our proposed experiments lay the fundamental groundwork for a better understanding of auditory cortex by studying for the first time the large-scale organization and plasticity of auditory cortex with single cell resolution.